Gas fired water heating appliances such as a pool water heater typically have a controller for controlling the supply of gas and an igniter for igniting the gas. An igniter known in the art that is capable of warming up quickly is a silicon nitride hot surface igniter. While such an igniter is desirable because of its mechanical strength and durability, it has a critical temperature limitation which must be avoided. Specifically the silicon nitride igniter must remain below approximately 1350° Celsius. If the igniter temperature repeatedly approaches 1350° C., the igniter will cease to ignite prematurely. Thus, electrical power to the igniter must be controlled to provide an igniter temperature that is sufficient to ignite gas and is below the 1350° C. temperature limitation.
Gas fired water heaters for pools typically require either a 120 volt or 240 volt alternating current power source for pump motors and other components. Controllers for such pool water heaters therefore had to be configured in either a 120 volt or 240 volt embodiment, for controlling the application of power to related components such as an igniter. This is particularly the case with the silicon nitride hot surface igniter, which requires careful control of power applied to the igniter to avoid its critical temperature. Such controllers are typically required to switch power to the igniter to provide an averaged applied voltage of a predetermined level from the line voltage power source. Therefore, the line voltage level of an existing pool water heater that is to be replaced is significant to the selection of the replacement water heater controller.